iron or copper pyrites, sometimes mistaken for gold.
Origin of fool's gold
An Americanism dating back to 1870–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
any of various yellow minerals, esp pyrite or chalcopyrite, that can be mistaken for gold
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Any of several minerals, especially pyrite and chalcopyrite, sometimes mistaken for gold.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.